Air Power: The Making of a Modern Wind Turbine and Wind Farm [Slide Show]
The amount of electricity produced from the wind continues to grow at a rapid clip, meaning more and more wind turbines dot the landscape
Credits: Courtesy of GE
HURLING ICE Although electricity from wind turbines can cut down on carbon dioxide emissions and other pollution, some people have found flaws—their noise (a constant hum when the wind blows), their propensity to kill birds or bats when improperly sited, and their ability to fling chunks of ice, as pictured here.
© Kathryn McCullough
WIND FARM To match the output of traditional power plants, hundreds of wind turbines are usually installed in one favorable location, such as the Klondike wind farm in Oregon pictured here. Even though the turbines sprawl to cover hectares of land, more traditional uses of the land—such as actual farming—can continue around them.
Courtesy of GE
GRID CONNECTION Each individual turbine generator is connected to a local grid that then feeds into the broader regional grid, which relays the electricity to consumers. One of the challenges of wind power is that the wind often blows best far away from where the most electricity is used—in densely populated metropolitan areas such as New York City and Los Angeles.
Courtesy of AWEA
BALANCE OF POWER The nacelle and blades weigh hundreds of metric tons and yet must be suspended 90 meters above the ground. This balancing act requires strong, all steel or steel-reinforced towers and concrete foundations.
© Sharon Vanderhey / Courtesy of AWEA Advertisement
GENERATOR All that spinning sets magnets in motion, generating an electrical field—just as steam sets a turbine spinning to turn magnets in a coal-fired or nuclear power plant. A typical, two-megawatt wind turbine today can generate more than 6,000 megawatt-hours of electricity a year from an induction generator that produces alternating current.
Courtesy of Vestas
GEARBOX Inside the gearbox are a series of gears that translate the relatively stately spinning of the blades—roughly 30 revolutions per minute—into the quick spin necessary to generate electricity—roughly 18,000 rpm. This is an expensive and heavy part of wind turbines, and some companies are replacing it with a so-called direct-drive generator tailored specifically to producing electricity from wind. Such generators rely on the permanent magnetic fields created by magnets made from rare earths, specifically neodymium.
Courtesy of Vestas
NACELLE The box atop a wind turbine's tower, set back from the blades and rotor, is known as a nacelle. This is essentially the cover for the machinery that translates wind power into electrical power, including the gearbox and generator.
Courtesy of AWEA
ROTOR The blades spin a rotor, which is attached to a shaft that transfers the torque it creates into the gearbox.
Courtesy of Vestas Advertisement
BREEZE BLADE The turbines rely for their turning power on massive blades most often made from fiberglass or aluminum. The blades can stretch 50 meters in length—and a modern turbine can have a diameter of more than 100 meters.
Courtesy of Alstom
WEATHER STATION A miniscule version of a wind turbine—an anenometer—measures wind speed and, along with a weather vane and other devices for measuring meteorological conditions, feeds that information into the turbine's computer. The computer then shifts the turbine's direction, pitch and yaw to best harvest the available wind energy. The computer can also be remotely controlled by the turbine's operators.
© David Biello
SPIN DOCTORING The three spinning blades are connected to a shaft, which turns with the breeze. That's not nearly fast enough to generate electricity with a regular generator, so in most wind turbines a gearbox uses that spin to turn secondary gears fast enough to twirl magnets in the generator. Simply put, the spinning magnets excite an electrical field in coiled copper or other conducting materials, and it is this electricity that then flows into the grid. A brake also shuts down the turbine if the winds become strong enough to break the turbine's internal components.
Courtesy of NREL
TOWER OF POWER A modern wind turbine towers 90 meters in the air and can sport three blades, each longer than a football field. When incoming wind blows across both faces of a blade, the unique shape causes a difference in air pressure between the faces. Just like with an airplane's wing, this difference in pressure lifts the blade, thereby spinning the turbine shaft.
© Kathryn McCullough Advertisement Advertisement